Virus-like particles (VLPs) are multiprotein structures that mimic the organization and conformation of authentic native viruses but lack the viral genome, potentially yielding safer and cheaper vaccine candidates. A handful of prophylactic VLP-based vaccines is currently commercialized worldwide: GlaxoSmithKline's Engerix® (hepatitis B virus) and Cervarix® (human papillomavirus), and Merck and Co., Inc.'s Recombivax HB® (hepatitis B virus) and Gardasil® (human papillomavirus) are some examples. Other VLP-based vaccine candidates are in clinical trials or undergoing preclinical evaluation, such as, influenza virus, parvovirus, Norwalk and various chimeric VLPs. Many others are still restricted to small-scale fundamental research, despite their success in preclinical tests. The implications of large-scale VLP production are discussed in the context of process control, monitorization and optimization. The main up- and down-stream technical challenges are identified and discussed accordingly. Successful VLP-based vaccine blockbusters are briefly presented concomitantly with the latest results from clinical trials and the recent developments in chimeric VLP-based technology for either therapeutic or prophylactic vaccination.
Up to now, VLP-based vaccines have been produced for more than 30 different viruses that infect human and other animals. The examples include AAV (Adeno-associated virus), H5N3 (Avian influenza), BFDV (Budgerigar fledgling disease virus), BTV (Bluetongue virus), Ebola, Enterovirus 71, GHPV (Goose hemorrhagic polyoma virus), HBV (Hepatitis B virus), HCV (Hepatitis C virus), HDV (Hepatitis δ virus), HEV (Hepatitis E virus), HIV, HPV (Human papillomavirus), IBDV (Infectious bursal disease virus), Influenza A, Influenza A H1N1, Influenza A H3N2, JC polymavirus, Margurg, MS2, IPCV (Indian peanut clump virus), NDV (Newcastle disease virus), No (Norovirus) Nv (Norwalk virus), PhMV (Physalis mottle virus), Polymavirus, PPV (Porcine parvovirus), RHDV (Rabbit hemorrhagic disease virus), Rotavirus, SARS, SIV (Simian immunodeficiency virus), SV40 (Simian virus 40), SVDV (Swine vesicular disease virus) and so on. (Expert Rev. Vaccines 9(10), 1149-1176, 2010).
To quickly generate large quantity of VLPs or vaccines for both pre-clinical and clinical trials, almost all drug development will face the same challenging obstacle of rapidly generating a high stable producer. Developing and identifying a stable cell line is a critical part of the development. However, to generate a stable cell line with high titer and good product quality is not so easily accomplished until now.
Chikungunya virus (CHIKV) has infected millions of people in Africa, Europe and Asia since this alphavirus reemerged from Kenya in 2004. The severity of the disease and the spread of this epidemic virus present a serious public health threat in the absence of vaccines or antiviral therapies. It is reported that a VLP vaccine for epidemic Chikungunya virus protects non-human primates against infection (Nat Med. 2010 March; 16(3): 334-338). US patent publication No. 2012/0003266 discloses a virus-like particle (VLP) comprising one or more Chikungunya viral structural proteins which is useful for formulating a vaccine or antigenic composition for Chikungunya that induces immunity to an infection or at least one symptom thereof. WO2012/106356 discloses modified alphavirus or flavivirus virus-like particles (VLPs) and methods for enhancing production of modified VLPs for use in the prevention or treatment of alphavirus and flavivirus-mediated diseases. (these cited references are herein incorporated by reference).